[fsp] Let extensions decide about the file system id.

chrome/browser/chromeos/file_system_provider/service.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_SERVICE_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_SERVICE_H_
 
 #include <map>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/values.h"
 #include "chrome/browser/chromeos/file_system_provider/observer.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 28 matching lines @@
 
   Service(Profile* profile, extensions::ExtensionRegistry* extension_registry);
   virtual ~Service();
 
   // Sets a custom ProvidedFileSystemInterface factory. Used by unit tests,
   // where an event router is not available.
   void SetFileSystemFactoryForTests(
       const FileSystemFactoryCallback& factory_callback);
 
   // Mounts a file system provided by an extension with the |extension_id|.
-  // For success, it returns a numeric file system id, which is an
-  // auto-incremented non-zero value. For failures, it returns zero.
-  int MountFileSystem(const std::string& extension_id,
-                      const std::string& file_system_name);
+  // For success, returns true, otherwise false.
+  bool MountFileSystem(const std::string& extension_id,
+                       const std::string& file_system_id,
+                       const std::string& file_system_name);
 
   // Unmounts a file system with the specified |file_system_id| for the
   // |extension_id|. For success returns true, otherwise false.
-  bool UnmountFileSystem(const std::string& extension_id, int file_system_id);
+  bool UnmountFileSystem(const std::string& extension_id,
+                         const std::string& file_system_id);
 
   // Requests unmounting of the file system. The callback is called when the
   // request is accepted or rejected, with an error code. Returns false if the
   // request could not been created, true otherwise.
-  bool RequestUnmount(int file_system_id);
+  bool RequestUnmount(const std::string& extension_id,
+                      const std::string& file_system_id);
 
   // Returns a list of information of all currently provided file systems. All
   // items are copied.
   std::vector<ProvidedFileSystemInfo> GetProvidedFileSystemInfoList();
 
   // Returns a provided file system with |file_system_id|, handled by
   // the extension with |extension_id|. If not found, then returns NULL.
   ProvidedFileSystemInterface* GetProvidedFileSystem(
       const std::string& extension_id,
-      int file_system_id);
+      const std::string& file_system_id);
 
   // Returns a provided file system attached to the the passed
   // |mount_point_name|. If not found, then returns NULL.
   ProvidedFileSystemInterface* GetProvidedFileSystem(
       const std::string& mount_point_name);
 
   // Adds and removes observers.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
   // Gets the singleton instance for the |context|.
   static Service* Get(content::BrowserContext* context);
 
   // extensions::ExtensionRegistryObserver overrides.
   virtual void OnExtensionUnloaded(
       content::BrowserContext* browser_context,
       const extensions::Extension* extension,
       extensions::UnloadedExtensionInfo::Reason reason) OVERRIDE;
 
  private:
-  typedef std::map<int, ProvidedFileSystemInterface*> ProvidedFileSystemMap;
-  typedef std::map<std::string, int> MountPointNameToIdMap;
+  // Key is a pair of an extension id and file system id, which makes it
+  // unique among the entire service instance.
+  typedef std::pair<std::string, std::string> FileSystemKey;
+
+  typedef std::map<FileSystemKey, ProvidedFileSystemInterface*>
+      ProvidedFileSystemMap;
+  typedef std::map<std::string, FileSystemKey> MountPointNameToKeyMap;
 
   // Called when the providing extension accepts or refuses a unmount request.
   // If |error| is equal to FILE_OK, then the request is accepted.
   void OnRequestUnmountStatus(const ProvidedFileSystemInfo& file_system_info,
                               base::File::Error error);
 
   Profile* profile_;
   extensions::ExtensionRegistry* extension_registry_;  // Not owned.
   FileSystemFactoryCallback file_system_factory_;
   ObserverList<Observer> observers_;
   ProvidedFileSystemMap file_system_map_;  // Owns pointers.
-  MountPointNameToIdMap mount_point_name_to_id_map_;
-  int next_id_;
+  MountPointNameToKeyMap mount_point_name_to_key_map_;
   base::WeakPtrFactory<Service> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Service);
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_SERVICE_H_